Does the deceased benefit from charity andfasting if he died when he was not praying?

My father has recently passed away.
He has missed many salaah during his lifetime. He has passed away at aged 65.
Is there any way of paying to charity any amount for the salaah missed.
Please advise how to calculate the number of salaah missed and the
amount to pay for charity for each day of salaah missed.
Eg. 65 years less 15 years= 50 years salaah missed. 50 years X 365
days = 18250 days of salaah missed.
Your assistance in answering the above will be greatly appreciated.
Praise be to Allaah.
Firstly:
The scholars differed on the ruling on one who neglects the prayer out
of heedlessness and laziness.The correct view is that heis a kaafir.
This has been discussed previously in the answers to questions no.
2182 and 5208 .
Once it is established that the one who does not pray is a kaafir, it
is not permissible to give charity, fast and do Hajj on his behalf.
The scholars of the Standing Committee (9/69) were asked: Is it
acceptable to pray for forgiveness and give charity for one who died
when he did not pray, or he used to pray sometimes and sometimes he
did not pray? Is it permissible to attend his funeral and bury him in
the Muslim graveyard?
They replied: The one who does not pray because he denies that it is
obligatory is a kaafir according to the consensus of the Muslims. The
one who does not pray out of heedlessness and laziness is a kaafir
according to the more correct of the two scholarly opinions.
Based on that, if a person who deliberately does notpray dies, it is
not permissible to pray for forgiveness for him, or to give charity on
his behalf, or to attend his funeral, orbury him in the Muslim
graveyard, because the Prophet (blessings and peace of Allah be upon
him) said: "The covenant that stands between us and them is the
prayer; whoever abandons it is a kaafir." Narrated by Ahmad and the
authors ofas-Sunan with a saheeh isnaad. And he (blessings and peace
of Allah be upon him) said: "Betweena man and kufr and shirk there
stands his giving up prayer." Narrated by Muslim in his Saheeh.
Standing Committee for Academic Research and Issuing Fatwas
Shaykh 'Abd al-'Azeez ibn 'Abdullah ibn Baaz … Shaykh 'Abd ar-Razzaaq
'Afeefi… Shaykh 'Abdullah ibn Ghadyaan… Shaykh 'Abdullah ibn Qa'ood
If your father was unaware that prayer is obligatory, or he
followedscholars who ruled that the one who does not pray out of
heedlessness is not a kaafir, then we hope that Allah will forgive
him, and in this case supplication and prayers for forgiveness forhim,
and giving charity onhis behalf, will benefit him.
And Allah knows best.